我們在本論文中研究電荷量子位元在懸浮平板中的消相干現象。在懸浮平板中，三種不同的聲波-SV波、P波會互相耦合造成色散關係中有群速度為零的地方，因而造成電子聲子交互作用在這個點特別強，所以要考慮非馬可夫效應。我們計算了雙量子點量子位元在線性疊加態的狀況下，受聲子作用所造成的消相位影響，除此之外，我們也考慮了兩個糾纏的量子位元受聲子的影響，所造成糾纏態在不同量子點距離、平板厚度的情況下，消相干係數的變化。

In this thesis, we investigate the pure-dephasing of charge qubits in the free-standing slab. The shear vertical and longitudinal waves can couple with each other in the free standing slab causing a singularity in the density of state. The electron-phonon interaction is relatively strong at this point. Therefore, one has to consider the non-Markovian effect near the singularity. We display the behaviors of the pure-dephasing for one-qubit state and two-qubit state. We also consider the effects of different slab widths and different distances between the qubits on the decoherent factor.

[1]N. Bannov, V. Mitin, and M. Stroscio, phys. stat. sol. (b) 183, 131 (1994).
[2]B.A.Auld, Acoustic fields and waves in solids (Wiley, New York, 1973).
[3]Y. Yamamoto, F. Tassone, and H. Cao Semiconductor cavity quantum electrodynamics (Berlin, Springer, 2000).
[4]T. Fujisawa, T. H. Oosterkamp, W. G. van der Wiel, B. W. Broer, R. Aguado, S. Tarucha, and L. P. Kouwenhoven, Science 282, 932 (1998).
[5]T. Fujisawa and S. Tarucha, Superlatt. Microstr. 21, 247 (1997).
[6]T. Brandes, The Dicke Effect in Electronic Systems (2000).
[7]William K. Wootters, Phys. Rev. Lett. 80, 2245 (1998).
[8]N. Bannov, V. Aristov, and V. Mitin, Phys. Rev. B 51, 15 (1995).
[9]V. N. Stavrou and Xuedong Hu, Phys. Rev. B 72, 075362 (2005).